The deodorant, aromatic agent, anti-fungal agent, insecticide, mothproofing agent, and the like, which are prepared by providing oily substances having volatility at room temperature or an increased temperature as active ingredients and impregnating predetermined carriers with the active ingredients, have been and are used as substitutes for conventional articles containing volatile gels or solids as active ingredients. Most of the above oily substances are odorless, and when they are used by impregnating carriers with the above odorless oily substances, it is difficult to ascertain even the time of expiration thereof, not to mention the remaining content thereof, by the human sense of smell. For this reason, there have been developed a variety of indicator materials which can visually show users the remaining time and the expiration time of the oily substances.
Among the above indicator materials are the following two indicator materials each of which is prepared by impregnating a non-woven fabric with the above oily substance and can visually show users the degree of the dissipation thereof which occurs with the passage of time.
One is a mothproofing material which also works as a mothproofing capability indicator, in which one surface of an oil-permeable paper-like material (including a non-woven fabric), which is altered into transparency when an oil (oily substance) is contained, is used as an indicating surface, an oil-impermeable pattern layer is formed on the entirety or part of the other surface of the paper-like material to obtain a substrate and the substrate is impregnated with an oil mothproofing agent volatile at room temperature (JP-B-4-36122).
In the above mothproofing material which also works as a mothproofing capability indicator, since the paper-like material is altered into transparency when an oil mothproofing agent is contained, the pattern layer provided on the other side can be visually observed. On the other hand, since the paper-like material is gradually brought into an original non-transparent state with the dissipation of the liquid oil, the pattern layer formed on the other side gradually becomes visually non-observable. Depending upon the pattern layer visually observable from the paper-like material side, therefore, users can visually know the degree of dissipation of the liquid oil (mothproofing chemical) which occurs with the passage of time.
The other one is a time length indicator prepared by consecutively applying a colorant, which is altered into transparency when a liquid volatile at room temperature penetrates it, to portions where the above contained liquid is dissipated earlier and later on the surface of a substrate sheet (including a non-woven fabric) into which a liquid containing the liquid volatile at room temperature is penetrable, such that the colorant form layers as time length indicating layers (Japanese Laid-open Utility Model Publication No. 5-14983). The above time length indicator uses the fact that when the substrate sheet containing the liquid volatile at room temperature is held horizontally, the liquid volatile at room temperature is easily successively dissipated from an edge portion of the substrate sheet surface and that when the substrate sheet containing the liquid volatile at room temperature is held vertically, the liquid volatile at room temperature is easily successively dissipated from the top of the substrate sheet. The time length indicator having a predetermined form is provided depending upon a pre-determined method of setting the time length indicator.
When the liquid is contained in the substrate sheet of the above time length indicator, the time length indicating layers show a transparent state, since the liquid penetrate the time length indicating layers. With the dissipation of the liquid contained in the substrate sheet, the amount of the liquid which has penetrated the time length indicating layers decreases, and the time length indicating layers accordingly become visually observable. Users can therefore know the degree of the dissipation of the liquid which occurs with the passage of time depending upon which time length indicating layer can be visually observed.
When a conventional non-woven fabric is impregnated with an oily substance volatile at room temperature or an increased temperature, the dissipation of the oily substance from the non-woven fabric does not take place uniformly. Therefore, when a conventional non-woven fabric is used as a paper-like material to prepare an indicator material having the same constitution as that of the above mothproofing material which also works as a mothproofing capability indicator, the pattern layer formed on the other side of the paper-like material becomes visually non-observable with the dissipation of the oily substance, while the visual sight thereof differs from one place to another on the paper-like material (non-woven fabric) and a spots-like pattern is observed. It is therefore difficult to clearly show the degree of dissipation of the oily substance which occurs with the passage of time with the above indicator material.
Further, a conventional non-woven fabric has the relatively low capacity to support the oily substance. That is, when the non-woven fabric is impregnated with the oily substance in an amount equivalent to, or smaller than, the volume of pores of the non-woven fabric, the capacity of the non-woven fabric to support the oily substance such that the oily substance does not seep is relatively low. Therefore, when a conventional non-woven fabric is used to prepare an indicator material having the same constitution as that of the above mothproofing material which also works as a mothproofing capability indicator, the indicator material can contain only a relatively small amount of the oily substance.
On the other hand, a conventional non-woven fabric is used as a substrate sheet to prepare an indicator material having the same constitution as that of the above time length indicator, the time length indicator layers do not relatively clearly show the degree of dissipation of the oily substance which occurs with the passage of time. Further, this indicator material can contain only a small amount of the oily substance. Moreover, when the indicator material is set by a method which is not predetermined when it is prepared, for example, when it is set slantly or upside down, the time length indicating layer showing a time length different from the time length which has actually passed is visually observed, and the setting site and the setting method are therefore limited.
It is an object of the present invention to provide an indicator material which can clearly indicate not only the time of expiration of the oily substance but also the degree of dissipation of the oily substance which occurs with the passage of time, regardless of a setting site and a setting method.